The action of many therapeutic neuropharmacological agents involve the modulation of dopamine (DA), norepinephrine (NE) and serotonin (5-HT) release, uptake and storage within their respective terminals in the central nervous system (CNS). Most neurotransmitters are stored in synaptic vesicles, which are prominent features of nerve terminals. Sequestration into vesicles appears to be responsible for maintaining a ready supply of neurotransmitter molecules available for neuronal exocytotic release into the synaptic cleft. Vesicles also serve the role of protecting the neurotransmitter molecules from metabolic breakdown. One transport site on the vesicle membrane is the vesicular monoamine transporter-2 (VMAT2), whose role is to transport transmitters from the cytosol into the synaptic vesicle. Once the neurotransmitter is released from the terminal into the synaptic space, it interacts with postsynaptic receptors and subsequently is taken back up into the terminal via the plasma membrane transporter (e.g., DAT and/or the serotonin transporter [SERT]). Thus, transporter proteins modify the concentration of neurotransmitters in the cytosolic and vesicular storage pools, and thereby have the ability to alter subsequent neurotransmission.